Measuring apparatus and method for determining the duration of the application of pressure in a rotary press



3,262,054 INING J ly 9, 96 R. LEFKOWITZ MEASURING APPARATUS AND METHODFOR DETERM THE DURATION OF THE APPLICATION OF PRESSURE IN A ROTARY PRESS2 Sheets-Sheet 1 Filed July 17, 1962 FIG.I

DETECTOR y 19, 1966 L. R. LEFKOWITZ 3,262,054

MEASURING APPARATUS AND METHOD FOR DETERMINING THE DURATION OF THEAPPLICATION OF PRESSURE IN A ROTARY PRESS Filed July 17, 1962 2Sheets-Sheet 2 25 A5 fi *FIG.6

Q no

--OSCILLOSCOPE TRAILING SWITCH 82 CLOSED FIG.7

FIG. 9

United States Patent York Filed July 17, 1962, Ser. No. 210,456 17Claims. (Cl. 32468) This invention relates to measuring apparatus andmethods and more particularly to apparatus and methods for makingparticular measurements as an article advances along a feed path.

Measuring apparatus and methods of the type to which the presentinvention is directed, while of general ap plication, are particularlywell suited for ascertaining the duration of the application of pressureto an article as it moves along a feed path. As an illustration, suchapparatus and methods advantageously may be employed in connection witha p apermaking machine, for example, to ascertain the time during whichpressure is applied to a papermakers felt or other paper web carrier asit moves through the nip between a pair of rollers on the machine.

As is well known in the papermaking field, paper is formed from a web ofwater saturated pulp which is transported by one or more papermakersfelts through opposed press rolls and/ or other dewatering devices untilthe moisture content of the web is reduced to a satisfactory level. Thefelts customarily are arranged in the form of endless belts which aremounted under tension on a series of drive rolls and support rolls withthe paper supporting portions extending through the nips between thepress rolls. As the paper supporting portion of a particular felt movesalong its feed path, the felt picks up considerable moisture from thewet paper web. To operate eflectively, a substantial quantity of thismoisture must be removed from the felt as it passes between the pressrolls.

To insure that a maximum quantity of moisture is removed from the feltas it is led through the nip between the press rolls, pressure should beapplied by the rolls for a controlled length of time. In addition, thedistance travelled by a given section of the felt while under thepressure and the speed of the felt also should be carefully controlled.It is therefore desirable to accurately measure these characteristics inorder that any necessary adjustments can be made to provide effectivemoisture removal.

Heretofore, difiioultiles have been encountered in the measurement ofparticular characteristics of a papermakers felt or other article movingalong a feed path. For example, in prior apparatusand methods for thispurpose, the measurements for the most part were made by applyingpressure to the felt during one or more static tests, and when the feltwas placed in operation on a paper machine additional factors wereintroduced which greatly reduced the accuracy of the test results. Inaddition, in many apparatus and methods of the type employed heretofore,the applied pressure was measured over a relatively wide area, with theresult that the accuracy and selectively of the individual measurementswere further reduced.

One general object of this invention, therefore, is to provide a new andimproved apparatus and method for making particular measurements onpapermakers felts or other articles.

More specifically, it is an object of this invention to provide anapparatus and method for making such measurements as the article isadvanced along a feed path.

Another object of this invention is to provide an apara- 3,262,054Patented July 19, 1966 nus and method of the character indicated formeasuring the duration of the application of pressure to the article inan accurate and straightforward manner.

A further object of the invention is to provide such an apparatus andmethod for measuring the rate of movement of the article as it advancesalong its path.

Still another object of the invention is to provide a measuringapparatus which is economical to manufacture and thoroughly reliable inoperation.

In one illustrative embodiment of the invention a switching device ofunique construction and arrangement is positioned adjacent a surface ofthe papermakers felt or other article to be measured. This device isformed from a pair of flexible, electrically conductive switch elementswhich are supported within an elongated envelope of dielectric material.The switch elements are separated by insulating means having twolongitudinally spaced apertures therein. As pressure is applied to theswitching device and the article, the portions of the switch elementsadjacent the apertures are urged into contact with each other to close acircuit and provide an electrical signal which is representative of thedesired measurements.

In accordance with one feature of the invention, in a representativeembodiment, the switch elements are urged into engagement with eachother only upon the application of a pressure greater than apredetermined pressure, with the result that a signal is detected onlywhen the applied pressure exceeds the predetermined pressure.

In accordance with another feature of the invention, in certainpreferred embodiments, the switching device is advanced along a feedpath simultaneously with the article to be measured. As a result, theoverall accuracy and reliability of the measurements are greatlyenhanced.

In accordance with still another feature of the invention, in certaingood arrangements, an alternating current of fixed frequency is suppliedto the switching dc vice, and the duration of the detected signal ismeasured to provide an indication of the time during which the appliedpressure exceeds the predetermined pressure.

In accordance with a further feature of certain embodimentsof theinvention, the switch elements are arranged to contact each other atparticular, discrete points, with the result that the device is highlyselective and provides an extremely accurate indication of the measuredtime interval.

The present invention, as well as further objects and features thereof,will be understood more clearly and fully from the following descriptionof certain preferred embodiments, when read with reference to theaccompanying drawings, in which: FIGURE 1 is an exploded perspectiveview of a switchmg device forming a part of measuring apparatus inaccordance with one illustrative embodiment of this invention which isuseful in practicing the method of the invention;

FIGURE 2 is a top plan view of the switching device of FIGURE 1;

FIGURE 3 is a schematic representation of a pair of press rolls andassociated components of a papermaking machine, together with theswitching device and other portions of the apparatus;-

FIGURE 4 is an enlarged fragmentary sectional view of a portion ofFIGURE 3;

FIGURE 5 is a fragmentary sectional view in general similar to FIGURE 4but showing the switching device as it is advanced through the nipbetween a pair of resilient rollers;

FIGURE 6 is a schematic wiring diagram of the apparatus;

FIGURE 7 is a schematic representation of an illustrative oscilloscopetrace showing representative measuring signals from the apparatus;-

FIGURE 8 is an exploded perspective view of a switching device forming apart of measuring apparatus in accordance with another illustrativeembodiment of the invention; and

FIGURE 9 is a vertical sectional view of the device of FIGURE 8, takenthrough a longitudinal, median plane.

Referring to FIGURES 1 and 2 of the drawings, there is shown a switchingdevice indicated generally at which include an elongated, substantiallyrectangular envelope 16 of insulating material. The envelope 16 isformed from two fiat sheets 18 and 19 which are adhesively securedtogether along abutting portions thereof and are fabricated from epoxyor other material having a comparatively high dielectric constant. Thesheets 18 and 19 are flexible and illustratively have a thickness ofabout two to five thousandths of an inch.

Interposed between the dielectric sheets 18 and 19 are two switchelements and 26 of flexible, electrically conductive material. Theelements 25 and 26 comprise relatively small diameter wires and includesinsulated portions 27 and 28, respectively, which protrude from one endof the envelope '16. The element 25 extends in a generally longitudinaldirection but is bent in the shape of a U adjacent its inner end to formtwo transversely extending legs 30 and 31. As best shown in FIGURE 2,these legs meet the remaining, longitudinal portions of the element 25at right angles.

The switching element 26 extends longitudinally and is laterally spacedwith respect to the longitudinal portions of the switch element 25. Theelement 26 crosses the legs 30 and 31 of the element 25 at right angles.The legs 30 and 31 serve as the contact portions of the element 2'5 andcooperate with corresponding contact portions 33 and 34, respectively,on the element 26.

The contact portions 30 and 3 1 are normally maintained in spacedrelationship with the corresponding contact portions 33 and 34 byinsulating means which, in the embodiment illustrated in FIGURES 1-6,comprises two comparatively thin washers 36 and 37 of dielectricmaterial. These washers include centrally located apertures 38 and 39,respectively, which are each of a diameter greater than the diameter ofthe wires forming the switch elements 25 and 26. The washer 36 ispositioned in the envelope 16 between the contact portions 30 and 33,while the washer 37 is oriented in the envelope between the con-tactportions 31 and 34.

The arrangement is such that the opposed pairs of contact portions #30and 33 and 3 1 and 34 on the elements 25 and 26 form two normally openswitches 40 and 41 which are connected in parallel in a circuit 42, asshown schematically in FIGURE 6. The external portion 27 of the element25 is releasably connected, as at 43, in series with a conductor 44leading to one terminal of a fixed frequency oscillator 45. The externalportion 28 of the element 26 leads to a releasable connection 46 andthen through a conductor 48 to one terminal of an oscilloscope 50. Aconductor 51 serves to interconnect the remaining terminals of theoscillator and the oscilloscope. As will be understood, the oscillatorgenerates an alternating current of known frequency which is appliedacross the elements 25 and '26. The generated frequency preferably is inthe medium frequency range and illustratively may be of the order of 10kilocycles at about five volts.

As best shown in FIGURES 3 and 4, the switching device 15 is adapted tobe advanced through the nip 54 between a pair of opposed press rolls 55and 56 of a papermaking machine. The roll 55 is mounted on a shaft 58,while the roll 56 is carried by a parallel shaft 59 which is journaledbetween two elongated arms 60 (only one of the arms 60 being visible inFIGURE 3). One pair of adjacent ends of these arms llS pivotallysupported, as at 62. The opposite arm ends are suitably connected to oneend of an upstanding plunger 63 having a piston 64 at its opposite endwhich is reciprocally mounted within a hydraulic cylinder 66. Thecylinder 66 includes the usual inlet conduit 67 through which fluidunder pressure is \introduced to control the spacing between the shafts58 and 59 and hence vary the pressure exerted between the press rolls.

A papermakers felt '71 is arranged in the form of an endless belt and issupported in the usual manner by a series of rolls 72. The felt ismaintained under tension by a pair of take-up rolls '74 and is directedalong a path such that the paper-supporting portion 76 thereof extendsin a substantially horizontal plane and passes through the nip 54between the press rolls 55 and 56. In most cases one or more of therolls 72 serves as a drive roll to advance the felt 70 along its feedpath, although in some situations, the felt may be driven by the pressrolls. As will be understood, the paper-supporting portion '76 serves tofeed the wet paper web (not shown) along this path and through the nip54, where the action of the rolls 55 and 56 squeezes some of themoisture from the web into the felt. The moisture preferably does notremain in the felt but is discharged as a result of the pressure exertedthereon by the press rolls.

In order to insure the removal of a maximum quantity of moisture fromboth the wet paper web and the felt as they pass through the nip 54, thedegree of compression of the felt should be carefully controlled. Thecompression of a given felt is determined by its normal, uncompressedthickness minus the compressed thickness at the longitudinal center ofthe nip 54. These factors are in turn related to the length of the feltunder pressure at a given time in accordance with the following formula:

h normal felt thickness lz =compressed felt thickness d=length of feltunder pressure R=press roll radius The length of the felt under pressure(the distance d in FIGURE 4) corresponds to the distance travelled by agiven felt section as it passes through the nip 54 and is referred toherein as nip distance. This distance is determined by the time requiredfor the felt section to pass through the nip and the speed of the felt.It is important to accurately measure these characteristics so that thedegree of compression of the felt can be calculated to ascertain theoptimum relative positions of the press rolls 55 and 56 for effectivemoisture removal.

The switching device 15 is arranged to close the circuit 42 and therebysupply a signal to the oscilloscope 50 only when the pressure applied tothe envelope 16 is greater than a predetermined pressure correspondingto the pressure needed between the press rolls 55 and 56 to begincompression of the felt 70. Thus, the thickness and flexibility of theenvelope 16 and the switch elements 25 and 26, as well as the dimensionsof the washers 36 and 37, are such that the contact portions 30 and 31engage the contact portions 33 and 34, respectively, only upon theapplication of the predetermined pressure. For papermaking applications,the pressure in most cases is somewhat less than one pound per squareinch, but the pressure may be set at substantially any desired level byvarying the configuration, dimensions, materials used, etc, of thedevice 15. Because of the resiliency of the elements 25 and 26, at thetime the pressure is removed from a given pair of contact portions theyimmediately return to their initial, spaced-apart positions.

In operation, the switching device 15 is supplied with alternatingcurrent of known frequency by manually connecting the protruding portion27 of the element 25 to the conductor 44 leading to the fixed frequencyoscilla- I 6) tor 45. The protruding portion 28 of the element 26 issimilarly connected to the conductor 48. The portions 27 and 28 arerelatively long, illustratively having a length of about five feet, forexample, and are releasably secured to their corresponding conductors bythe connections 43 and 46. The elements and 26 are positioned insufiicient proximity with each other so that, upon their connection tothe conductors 44 and 48, a small amount of leakage occurs between theopposed contact portions 30 and 33 and 31 and 34. As a result, a lowamplitude sign wave signal 78 (FIGURE 7) of a frequency equal to that ofthe oscillator appears on the oscilloscope 50, for purposes that willbecome more fully apparent hereafter.

The switching device 15 is positioned on the portion 76 of the felt 70and is longitudinally aligned with respect to the direction of movementthereof along its feed path. The device 15 is carried by the felt intothe nip 54 between the opposed press rolls 55 and 56. As best shown inFIGURE 4, the device becomes more or less imbedded in the upper surfaceof the felt by the pressure exerted thereon by the press rolls. Thispressure is applied to the switch elements 25 and 26 by the roll 56 andthe felt and tends to move the elements 25 and 26 toward each otheradjacent their contact portions. In cases in which the applied pressureis greater than the predetermined pressure for which the switch isdesigned, the leading contact portions 30 and 33 (FIGURE 1) are urgedinto momentary engagement by reason of the aperture 38 in the washer 36.A series circuit is thereby completed from one terminal of theoscillator 45, the conductor 44, the releasable connection 43, theelement 25, the switch 40, the element 26, the releasable connection 46,the conductor 48, the oscilloscope and the conductor 51 to the otherterminal of the oscillator. Upon the completion of this circuit, theamplitude of the signal applied to the oscilloscope is increasedsubstantially until the switch 40 passes through the nip 54, at whichtime the amplitude of the applied signal returns to its initial level.The longitudinal spacing between the leading pair of contact portions 30and 33 and the trailing pair 31 and 34 is such that, after the leadingpairmakes and breaks the circuit, the trailing pair closes momentarilyto operate the switch 41 and again increase the amplitude of the signal.As the switch 41 passes through the nip and the pressure is removed, thesignal is again restored to its initial amplitude.

FIGURE 7 is illustrative of a typical oscilloscope trace obtained duringthe passage of the switching device 15 and the papermakers felt 70through the nip 54. For some paper machines the complete signal sweep,which travels from left to right across the oscilloscope screen, maytypically take place in about ten to twenty thousandths of a second. Theoscilloscope is adjusted in accordance with well known techniques sothat the increased amplitude signal resulting from the closing of theswitch 40 triggers or fires the scope trace at a predetermined startingposition on the left side of the screen, as viewed in FIGURE 7, fromwhich position the trace continues to sweep across the screen to producethe sine wave output signal illustrated in this figure. From left toright in FIGURE 7, the following events are shown: a signal 80 appearson the scope and represents the increased amplitude sine wave producedwhile the leading switch 40 remains closed due to the pressure exertedupon it as it passes through the nip 54. The signal on the scope thenchanges to the very low amplitude sine wave signal 78 of the samefrequency. This signal 78 is of an amplitude which illustratively isabout one-tenth the amplitude of the signal 80 and results from thesmall amount of leakage which continues to flow when the switches 40 and41 are open. Thereafter, an increased amplitude signal 82 appears at thetime the switch 41 undergoes compression and is closed as it passesbetween the rolls 55 and 56. Finally, a second low amplitude signal 79begins when the switch 41 opens as it passes out of the nip.

To ascertain the time during which a given section of the felt issubjected to a pressure greater than the pre determined pressure as itmoves through the nip 54, the number of cycles of exiciting frequency inthe signal 80 is counted, as by suitable counting apparatus (not shown)or by examining a photograph of the scope trace, for example, and isdivided by the fixed frequency, in cycles per unit time, of theoscillator 45. The resulting quotient provides an extremely accurateindication of the time during which a section of the felt is subjectedto this pressure.

The time between the closure of the switch 40 and that of the switch 41corresponds to the distance between a given point on the sine waveindicated by the reference character 80 and a corresponding point on thesine wave indicated by the reference character 82. By measuring theelapsed time between sequential switch closures, e.g., the time betweenthe opening of the contact portions 30 and 33 and the opening of thecontact portions 31 and 34, for example, the speed of the felt as itpasses through the nip 54 is readily calculated. To accomplish this, theelapsed time, which is represented at A in FIGURE 7, is ascertained byadding the total number of cycles of the leakage signal 78 between thesignals 80 and 82 and the total number of cycles of the signal 82 andthen dividing by the fixed frequency of the oscillator 45. To calculatefelt speed, the time is divided into the longitudinal separation betweenthe leading and trailing pairs of contact portions, thereby providing anaccurate indication of the speed of the felt (or the peripheral speed ofthe press rolls) as it advances along its feed path.

In cases in which it is advantageous or desirable to determine thedistance 01 (FIGURE 4) travelled by a given section of the felt whilepassing through the nip 54 under a pressure greater than thepredetermined pressure, the speed of the felt'fs multiplied by the timethe felt section is subjected to this pressure. The time under pres sureis calculated from the number of cycles in the signal '80 in the mannerindicated heretofore and may be checked by counting the number of cyclesin the signal 82. The resulting nip distance is then used to calculatethe degree of compression of the felt in accordance with the aboveformula.

The length of the insulated portions 27 and 28 of the switching elements25 and 26, respectively, is sufficient to permit the switching device 15to pass completely through the nip 54. Thereafter, the portions 27 and28 are automatically disconnected by the releasable connections 43 and46 in the circuit 42.

Should the signals detected by the oscilloscope 50 indicate that thevarious measured characteristics of the felt are not consistent with theefficient removal of moisture therefrom, the position of the press roll56 relative to that of the press roll 55 is adjusted by varying thefluidpressure applied to the conduit 67. The apparatus is thereby adapted toprovide optimum moisture removal throughout a wide range of operatingconditions.

Referring now to FIGURES 8 and 9, there is shown a switching device 85which is representative of another, illustrative embodiment of theinvention. The device 85 is enclosed within a surrounding enevelope 86which is fabricated from two elongated, substantially flat sheets 88 and89 of dielectric material in a manner similar to the envelope 16(FIGURE 1) described heretofore. A pair of opposed switch elements 90and 91 of spring steel or other electrically conductive sheet materialare interposed between the dielectric sheets 88 and 89. The thickness ofthese elements illustratively is of the order of two to five thousandthsof an inch. The switch element 90 is of substantially E-shapedconfiguration and includes three legs 94, and 96 which extend indirections transverse to the longitudinal direction of the envelope 86.The legs 94 and 95 are comparatively narrow and serve as contactportions, while the leg 96 is substantially wider and is soldered orotherwise electrically connected to a conductor 98. The switch element91 is in the form of an elongated, flat plate which extendslongitudinally with respect to the envelope and is electricallyconnected to a conductor 99.

Positioned between the switch elements 96) and 91 is a thin sheet 100 ofhigh dielectric strength paper, plastic or other insulating material.The sheet 180 is provided with two apertures 102 and 103 therein whichare spaced apart in a longitudinal direction and, as best shown inFIGURE 9, are oriented immediately adjacent the contact portions 94 and95, respectively, of the switch element 90. The apertures 192 and 103are interposed between the contactportions 94 and 95 and correspondingcontact portions 105 and 106 on the switch element 91.

The various components of the switching device 85 are ladhesivelysecured together to form a sandwich-like construction having alternatelayers of non-conductive and conductive material. The assembled deviceis of relatively small thickness which illustratively is in theneighborhood of fifteen to twenty thousandths of an inch.

The device 85 is supplied with alternating current of known, fixedfrequency in a manner similar to that described above with respect tothe switching device d5. Thus, the conductor 98 is releasably connectedto the conductor 44, (FIGURE 6) leading to one side of the oscillator45, while the conductor 99 is similarly secured to the conductor 48connected through the oscilloscope 50 and the conductor 51 to theopposite side of the oscillator' The device 85 is longitudinallypositioned on the papermakers ielt 70 (FIGURE 3) as it moves along itsfeed path toward the nip 54 between the opposed press rolls 55 and 56.As the device 85 passes between the press rolls, alternating currentsignals of the type shown at 80 and S2 in FIGURE 7 appear on theoscilloscope. These signals are measured in a manner similar to thatdiscussed heretofore to provide an indication of particularcharacteristics of the felt as it passes through the nip 54.

In the illustrated embodiments of the invention, the switching devicesand 85 each have a thickness that advantageously is less than abouttwenty thousandths of an inch. With this arrangement, the device may beadvantageously employed to make exceedingly accurate measurements underproduction conditions without marring the surfaces of the press rolls orotherwise damaging the papernialcin g machinery. Additionally, in casesin which the device is advanced through the press roll nipsimultaneously with the paper web, the possibility of severing orotherwise injuring the web is substantially eliminate-d.

In other good embodiments, the thickness of the device 15 or 85, as thecase may be, is greater than that specifically indicated, again withgood results.

In certain embodiments of the invention, particularly in cases in whichvarious characteristics related to time are to be measured, theconfiguration and arrangement of the switching device advantageously issuch that the opposed contact portions thereof are engage ab-le witheach other at a particular, discrete point. Thus, in the switchingdevice '15 illustrated in FIGURES l6, ior example, the diameters of thewires forming the switch elements and 26 are such, in relation to thediameters of the apertures 3-8 and 39, that each of the contact portions30 and 31 on the element 25 engages the corresponding contact portion'36 or 34 on the element 26 only at a single, predetermined pointthere/between. Similarly, in the switching device 85 shown in FIGURES 7and 8, the dimensions of the contact portions 9 and 9-5 on the switchelement 90, when measured in a direction parallel to the longitudinaldirection of the device 85, and the diameters of the apertures 102 and1103 are such that the cont-act port-ions 94 and '95 engage theircorresponding contact portions 195 and 106 on the switch element 1% onlyat particular, discrete points. By providing such sensing points, asopposed to enlarged contact areas, the precise times at which thecontacts close and open are readily ascertaina'ble upon examination ofthe trace on the oscilloscope.

As indicated heretofore, in certain particularly advantageousembodiments of the invention, the switching device 15 or 85, as the casemay be, is advanced simultaneously with a papermakers felt through anopposed pair of pressureepplying rollers to measure particularcharacteristics of the felt. in other good arrangements, measurementsmay be made on other articles, and certain of these measurements may beascertained by maintaining the switching device and the article in astationary position and applying external pressure thereto. In addition,the switching device may be held stationary and the article advancedthereover to apply the pressure, as in cases in which it is desired todetermine the number of articles, for example, passing a given point.

Although the switching devices 15 and have been described as beingparticularly useful in the measurement of certain characteristics of anarticle during the application of pres-sure thereto, it will be apparentto those skilled in the art that the invention also may be employedladvantageously 'for other applications where the making of particularmeasurements is either necessary or desirable. Thus, as best shown inFIGURE 5, the device 15, for example, illustratively may be used tomeasure the characteristics of the nip 168 between a pair of opposedrollers M0 and 11 1 of rubber or other iesilient material. The device 15is advanced through the nip 168 to urge the contact portions 30 and 3 1into sequential engagement with their corresponding contact portions 33and 34 and thereby provide successive switch closures. These closuresproduce an oscilloscope trace of the type shown in FIG- URE 7 and enablethe calculation, in a manner similar to that described heretofore, ofsuch characteristics as the length of the nip, measured in the directionof travel of the device :15, and the peripheral speed of the rollers.

The terms and expressions which have been employed are used 'as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions, :of excluding any equivalents of thefeatures shown and described, or portions thereof, it being recognizedthat various modifications are possible within the scope of theinvention claimed.

What is claimed is:

1. Apparatus for measuring the duration of the application of pressuregreater than a predetermined pressure to a papermakers felt, comprising,in combination, an elongated substantially fiat envelope or flexibledielectric material, a first and a second electrically conductive switchelement positioned in spaced relationship with each other within saidenvelope, each of said switch elements having a contact portion thereon,insulating means interposed between said switch elements for maintainingthe same in spaced relationship with each other, said insulating meansincluding an aperture between said contact portions to permit movementthereof into and out of engagement only in response to the applicationof pressure greater than a predetermined pressure to said envelope,means for simultaneously applying pressure to said papermakers felt andsaid envelope, to move said contact portions into and then out ofengagement upon the application of pressure greater than saidpredetermined pressure, and means electrically connected to said switchelements for measuring the time said contact portion-s are inengagement.

2. Apparatus for measuring the duration of the application of pressureto a papermakers felt as it advances along a feed path comprising, incombination, an elongated substantially flat envelope of flexibledielectric material, a first and a second electrically conductive switchelement positioned in spaced relationship with each other within saidenvelope, each of said switch elements having a contact portion thereon,insulating means interposed between said switch elements rfiormaintaining the same in spaced relationship with each other, aidinsulating means including an aperture between said contact portions topermit movement thereof into and out of engagement in response to theapplication of pressure to said envelope, pressureapplying meansdisposed along said feed path, means for advancing said envelope andsaid papermakers felt through said pressure-applying means, to move saidcontact port-ions into and then out of engagement with each other, meansfor supplying an alternating current signal to said switch elements, andmeans connected to said switch elements for measuring the duration ofthe changes in said signal which result from engagement between saidcontact portions.

3. In apparatus for making particular measurements as an articleadvances along a .feed path, in combination, an elongated substantiallyflat envelope of dielectric material, a first and a second flexible,electrically conductive switch element positioned in spaced relationshipwith each other within said envelope, each of said switch elementshaving spaced-apart contact portions thereon, insulating meansinterposed between the contact portions on one of said switch elementsand those on the other of said switch element, said insulating meansincluding a pair of spaced apertures to enable movement of the contactportions on one of said switch elements into sequential engagement withcorresponding contact port-ions on the other said switch element inresponse to the application of pressure to said envelope,pressure-applying means disposed along said feed path, and means foradvancing said envelope and said article through said pressure-applyingmeans to move one pair of corresponding contact portions into and out ofengagement and to thereafter move the other pair of correspoding contactportions into and out of engagement.

4. Measuring apparatus of the character set forth in claim 3 in whicheach of said switch elements comprises an elongated wire extend-ing in asubstantially longitudinal direction with respect to said envelope andsaid insulating means includes a pair of Washers of dielectric materialrespectively disposed between said pairs of corresponding contactportions.

5. Measuring apparatus of the character set forth in claim 3 in whichsaid first switch element includes a pair of legs extending indirections transverse to the direction of movement of said envelope andsaid second switch element includes a longitudinally disposed plateengageable with each of said legs.

6; Apparatus for measuring the duration of the application of pressureto a papermakers felt as it passes through the nip between two rollerscomprising, in combination, an elongated substantially flat envelope offlexible dielectric material, a first and a second electricallyconductive switch element positioned in spaced relationship with eachother Within said envelope, each of said switch elements havingspaced-apart contact portions thereon, insulating means interposedbetween the contact portions on one of said switch elements and those onthe other of said switch element, said insulating means including a pairof spaced apertures to enable movement of the contact portions on one ofsaid switch elements into sequential engagement with correspondingcontact portions on the other said switch element in response to theapplication of pressure greater than a predetermined pressure to saidenvelope, means for advancing said envelope and said papermakers feltthrough the nip between said rollers to move corresponding contactportions into and out of engagement with each other, each Olf thecontact portions on said one switch element engaging the correspondingcontact portion on said other switch elemet at a particular, discretepoint, means releasably connected to said switch elements for supplyingan alternating current signal thereto, and means connected in serieswith said switch elements iior detecting changes in the amplitude ofsaid signal, to enable measurement of the time at least one pair ofcorresponding contact portions are in engagement and the time betweenthe engagement of successive pairs of corresponding contact portions.

7. A method of measuring the duration of the applica- 10 tion ofpressure to a papermakers felt as it passes through the nip between tworollers which comprises supplying an electrical signal to a switchingdevice including a first and a second switch element positioned Withinan envelope and maintained in spaced relationship with each other, eachof said switch elements having a contact portion thereon, advancing saidswitching device and said papermakers felt through the nip between saidrollers to move the contact portions of said switch elements into andout of engagement in response to the application of pressure thereto bysaid rollers, to thereby provide a switch closure, detecting the changesin said signal which result from said closure, and measuring the timeduration of said changes.

-8. A method of making particular measurements as an article advancesalong a path which comprises supplying an alternating current signal toa switching device including a first and a second electricallyconductive switch element positioned in spaced relationship with eachother within an enclosing envelope, each of said switch elements havingspaced-apart contact portions thereon, ad.- vancing said switchingdevice and said article through pressure-applying means disposed alongsaid path, to move the contact portions on one of said switch elementsinto sequential engagement with corresponding contact portions on theother switch element and thereby provide sequential switch closures,detecting changes in said signal which result from said switch closures,and measuring the time duration of said changes.

9. A method of making particular measurements as an article advancesalong a feed path which comprises supplying an alternating currentsignal of known frequency to a switching device including a first and asecond electrically conductive switch element positioned in spacedrelationship with each other, each of said switch elements having a pairof contact portions thereon, the contact portions on said first switchelement being spaced in sufiicient proximity with the correspondingcontact portions on said second switch element to permit thetransmission of a part of said signal therebetween, advancing saidswitching device and said article through pressureapplying meansdisposed along said path, to move the contact portions on one of saidswitch elements into sequential engagement with corresponding contactportions on the other switch element and thereby increase the amplitudeof the signal transmitted therebetween, each of the contact portions onsaid first switch element engaging the corresponding contact portion onsaid second switch element at a particular, discrete point, detectingthe increase in amplitude of said signal which results from engagementbetween at least one pair of said corresponding contact portions, andmeasuring the time duration of said increase.

10. A method of making particular measurements as an article advancesalong a feed path which comprises supplying an alternating currentsignal of known fre quency to a switching device including a first and asecond electrically conductive switch element positioned within anenvelope and maintained in spaced relationship with each other, each ofsaid switch elements having spacedapart contact portions thereon,advancing said switching device and said article throughpressure-applying means disposed along said path, to move the contactportions on one of said switch elements into sequential engagement withcorresponding contact portions on the other switch element in responseto the application of pressure thereto, each of the contact portions onsaid first switch element engaging the corresponding contact portion onsaid second switch element at a particular, discrete point, detectingchanges in the amplitude of said signal which result from engagementbetween at least one pair of said corresponding contact portions,measuring the time duration of said amplitude changes, and convertingsaid measurement into a factor representative of the distance travelledby the article during the application of said pressure.

11. A method of making particular measurements as an article advancesalong a feed path which comprises supplying an alternating currentsignal of fixed frequency :to a switching device including a first and asecond electrically conductive switch element positioned in spacedrelationship with each other, each of said switch elements havingspaced-apart contact portions thereon, advancing said switching deviceand said article through pressureapplying means disposed along saidpath, to move the contact portions on one of said switch elements intosequential engagement with corresponding contact portions on the otherswitch element in response to the application of pressure to said devicein excess of a predetermined pressure, detecting changes in said signalwhich result from engagement between said corresponding contactportions, measuring the time duration of the changes resulting fromengagement between at least one pair of contact portions, and measuringthe elapsed time between the engagement of successive pairs of contactportions.

12. A method of making particular measurements as an article advancesalong a feed path which comprises supplying an alternating currentsignal of fixed frequency to a switching device including -a first and asecond electrically conductive switch element positioned within anenvelope and maintained in spaced relationship with each other, each ofsaid switch elements having spaced-apart contact portions thereon,advancing said switching device and said article throughpressure-applying means disposed along said path, to move the contactportions on one of said switch elements into sequential engagement withcorresponding contact portions on the other switch element and therebyprovide sequential switch closures when the pressure on said deviceexceeds a predetermined pressure, each of the contact portions on saidfirst switch element engaging the corresponding contact portion on saidsecond switch element at a particular, discrete point, detecting changesin said signal which result from said switch closures, measuring thetime duration of the changes resulting from at least one of saidclosures, measuring the elapsed time between said closures, andconverting said measurements into respective factors representative ofthe distance travelled by said article during the application ofpressure greater than said predetermined pressure and the rate ofmovement of said article along said path.

13. A method of measuring particular characteristics of a papermakersfelt as it passes through the nip between two rollers which comprisessupplying an electri cal signal to a switching device including a firstand a second electrically conductive switch element positioned in spacedrelationship with each other, each of said switch elements havingspaced-apart contact portions thereon, advancing said switching deviceand said papermakers felt through the nip between said rollers, to movethe contact portions on one of said switch elements into sequentialengagement with corresponding contact portions on the other switchelement and thereby provide sequential switch closures when the pressureon said device exceeds a predetermined pressure, detecting changes insaid signal which result from said switch closures, measuring the timeduration of the changes resulting from at least one of said closures,measuring the elapsed time between said closures, and converting saidmeasurements into respective factors representative of the distancetravelled by the felt during the application of pressure greater thansaid predetermined pressure and the rate of movement of said feltthrough said nip.

14. A method of measuring particular characteristics of a papermakersfelt as it passes through the nip between two rollers which comprisessupplying an alternating current signal of fixed frequency to aswitching device including a first and a second electrically conductiveswitch element positioned within an envelope and maintained in spacedrelationship with each other, each of said switch elements havingspaced-apart contact portions thereon, advancing said switching deviceand said papermakers felt through the nip between said rollers, to movethe contact portions on one of said switch elements into sequentialengagement with corresponding contact portions on the other switchelement and thereby provide sequential switch closures when the pressureon said device exceeds a predetermined pressure, each of the contactportions on said one element engaging the corresponding contact portionon said other element at a particular, discrete point, detecting changesin the amplitude of said signal which result from said switch closures,measuring the time duration of the amplitude changes resulting from atleast one of said closures, measuring the elapsed time between saidclosures, and converting said measurements into respective factorsrepresentative of the distance travelled by the felt during theapplication of pressure greater than said predetermined pressure and therate of movement of said felt through said nip.

15. Apparatus for measuring the duration of the application of pressureto an article as it advances along a feed path comprising, incombination: a switching device including a substantially flat envelopehaving a thickness not in excess of about twenty-thousandths of an inch,a pair of switch elements of electrically conductive material positionedwithin said envelope, each of said switch elements having a contactportion thereon, and insulating means interposed between said switchelements for normally maintaining the same in spaced relationship witheach other but for permitting movement of said contact portions into andout of engagement in response to the application of pressure to saidswitching device; pressure-applying means disposed along said feed path;means for advancing both said switching device and said article alongsaid feed path and through said pressure-applying means tosimultaneously apply said pressure to said device and said article, tothereby move said contact portions into and then out of engagement;means for supplying an alternating current signal of predetermined fixedfrequency to said switch elements; and means electrically connected tosaid switch elements for detecting the changes in amplitude of saidsignal which result from the engagement between said contact portions.

16. Apparatus for measuring the duration of the application of pressureto an article as it advances along a feed path comprising, incombination: a switching device including a substantially flat envelopehaving a thickness not in excess of about twenty-thousandths of an inch,a pair of spaced-apart switch elements of electrically conductivematerial positioned within said envelope, each of said switch elementshaving a plurality of spaced contact portions thereon, and insulatingmeans interposed between said switch elements for normally maintainingthe same in spaced relationship with each other, said insulating meansincluding a pair of spaced apertures for permitting movement of thecontact portions on one of said switch elements into sequentialengagement with corresponding contact portions on the other said switchelement only in response to the application of pressure greater than apredetermined pressure to said switching device; pressure-applying meansdisposed along said feed path; means for advancing both said switchingdevice and said article along said feed path and through saidpressureapplying means to move said contact portions into saidsequential engagement in response to pressure greater than saidpredetermined pressure; means for supplying an alternating currentsignal of predetermined fixed frequency to said switch elements; anddetecting means electrically connected to said switch elements fordetecting the changes in amplitude of said signal which result from theengagement between successive pairs of said contact portions.

17. Apparatus of the character set forth in claim 16, in which saidspaced-apart switch elements are in sufficient proximity with each otherto provide a low amplitude signal on said detecting means in the absenceof engagement between said contact portions.

(References on fciluwing page) References Cited by the Examiner UNITEDSTATES PATENTS Edwards et a1 100-99 Chatterjea et a1 32468 Fleming200-86 En Dean et a1 73-40.5

Larson 200-86 14 RICHARD B. WILKINSON, Primary Examiner.

FREDERICK M. STRADER, Examiner. c. W. HOFFMANN, M. I. LYNCH,

Assistant Examiners.

6. APPARATUS FOR MEASURING THE DURATION OF THE APPLICATION OF PRESSURETO A PAPERMAKER''S FELT AS IT PASSES THROUGH THE NIP BETWEEN TWO ROLLERSCOMPRISING, IN COMBINATION, AN ELONGATED SUBSTANTIALLY FLAT ENVELOPE OFFLEXIBLE DIELECTRIC MATERIAL, A FIRST AND A SECOND ELECTRICALLYCONDUCTIVE SWITCH ELEMENT POSITIONED IN SPACED RELATIONSHIP WITH EACHOTHER WITHIN SAID ENVELOPE, EACH OF SAID SWITCH ELEMENTS HAVINGSPACED-APART CONTACT PORTIONS THEREON, INSULATING MEANS INTERPOSEDBETWEEN THE CONTACT PORTIONS ON ONE OF SAID SWITCH ELEMENTS AND THOSE ONTHE OTHER OF SAID SWITCH ELEMENT, SAID INSULATING MEANS INCLUDING A PAIROF SPACED APERTURES TO ENABLE MOVEMENT OF THE CONTACT PORTIONS ON ONE OFSAID SWITCH ELEMENTS INTO SEQUENTIAL ENGAGEMENT WITH CORRESPONDINGCONTACT PORTIONS ON THE OTHER SAID SWITCH ELEMENT IN RESPONSE TO THEAPPLICATION OF PRESSURE GREATER THAN A PREDETERMINED PRESSURE TO SAIDENVELOPE, MEANS FOR ADVANCING SAID ENVELOPE AND SAID PAPERMAKERS'' FELTTHROUGH THE NIP BETWEEN SAID ROLLERS TO MOVE CORRESPONDING CONTACTPORTIONS INTO AND OUT OF ENGAGEMENT WITH EACH OTHER, EACH OF THE CONTACTPORTIONS ON SAID ONE SWITCH ELEMENT ENGAGING THE CORRESPONDING CONTACTPORTION ON SAID OTHER SWITCH ELEMENT AT A PARTICULAR, DISCRETE POINT,MEANS RELEASABLY CONNECTED TO SAID SWITCH ELEMENTS FOR SUPPLYING ANDALTERNATING CURRENT SIGNAL THERETO, AND MEANS CONNECTED IN SERIES WITHSAID SWITCH ELEMENTS FOR DETECTING CHANGES IN THE AMPLITUDE OF SAIDSIGNAL, TO ENABLE MEASUREMENT OF THE TIME AT LEAST ONE PAIR OFCORRESPONDING CONTACT PORTIONS ARE IN ENGAGEMENT AND THE TIME BETWEENTHE ENGAGEMENT OF SUCCESSIVE PAIRS OF CORRESPONDING CONTACT PORTIONS.